PLATE VI. 



1 i. Group o( eight spicules of Peltastisis cornuta Nutting. a, one of the opercular spicules; b, one of 

 the spindles of the ccenenchyma; j, r , a spicule intermediate betweer) the calyx scales and the 

 spindles of the ccenenchyma; c, tl, c, f, i, scales from the calyx walls. All 120. 



i I »nc of the "bony stays" consisting of a single peculiar spicule of Peltastisis cornuta Nutting ■ 64. 



i Group of five spicules from Peltastisis uniserialis Nutting 120. e, one of the characteristic trian- 



gular spicules of the operculum; a, b, c, spindles from the ccenenchyma; d, calyx scale. 



i 4. Group of -ix spicules, <>. b, <'. </. <-. /, from Mopsea al/m Nutting X 120. 



:. t'.ilyx of Peltastisis cornuta Nutting 64. op., opercular scale; .>'. curious "bony stay" which is 

 formed of a single very large spicule and supports the calyx in front. 



